In order to study the propagation characteristics of the flame generated by ignition charge combustion in the propellant pellet packed bed under the ignition transmission structure of the central fire tube， a porous media model was used to simulate the gun propellant pellet packed bed in the propellant chamber， the flow and propagation process of high temperature and high speed gas generated by the combustion of ignition charge in the gun propellant pellet bed is simulated by using the N-S equation， the isothermal surface propagation of the temperature field is equivalent to the flame front propagation， and the simulation results were compared with those of experimental data. The results show that in the case of a dense charge bed of propellant， the isothermal surface is equivalent to the flame front in the process of ignition flame propagation， and the simulation value of flame propagation velocity is 91 m·s^-1， which is close to 96 m·s^-1 obtained by experiment；the simulated cloud images of temperature field of high temperature flame gas propagation are consistent with those of the experimental flame propagation images； the pressure data at the three pressure measuring holes in the chamber calculated by the porous media model are in good agreement with those of experimental data.